Hilton hit up the Playboy Mansion's Halloween party, joined by 22-year-old boyfriend River Viiperi and her mom, Kathy, and sister, Nicky.

The heiress and occasional DJ and singer donned a teddy bear onesie similar to the one from which Cyrus stripped for her collabo with Robin Thicke. Hilton didn't go all out and shave her head, but she did sport Cyrus' mini buns atop her blond noggin. Instead of looking entirely silly, Hilton actually made the outfit look classy and pretty -- the former being no small feat for the famed hard partier and sex tape starlet.